added fallback in the catch block

lib/single-file/modules/css-fonts-alt-minifier.js

@@ -277,7 +277,7 @@ this.singlefile.lib.modules.fontsAltMinifier = this.singlefile.lib.modules.fonts
 				try {
 					return node.property == propertyName && !cssTree.generate(node.value).match(/\\9$/);
 				} catch (error) {
-					// ignored
+					return node.property == propertyName;
 				}
 			}).tail;
 		}